How does Tor client build circuits when using a bridge?

1. How does Tor bridge work?
2. What problem do Tor bridges solve?

How does Tor bridge work?

The technology used by Tor bridges is designed to circumvent censorship where connections to Tor are blocked, for example in some countries with heavy censorship, by some public networks, or by some parental controls. It does so by camouflaging your connection so it cannot be recognized as a connection to Tor.

What problem do Tor bridges solve?

Abstract—Tor is a well-known low-latency anonymous communication system that is able to bypass the Internet censorship. However, publicly announced Tor routers are being blocked by various parties. To counter the censorship blocking, Tor introduced non-public bridges as the first-hop relay into its core network.